On 19/04/24 17:04, Sughosh Ganu wrote:
On Fri, 19 Apr 2024 at 16:04, Chintan Vankar c-vankar@ti.com wrote:
On 18/04/24 17:30, Sughosh Ganu wrote:
On Thu, 18 Apr 2024 at 16:08, Chintan Vankar c-vankar@ti.com wrote:
On 17/04/24 21:34, Tom Rini wrote:
On Wed, Apr 17, 2024 at 05:48:31PM +0530, Sughosh Ganu wrote:
hi Chintan,
On Wed, 17 Apr 2024 at 13:21, Chintan Vankar c-vankar@ti.com wrote: > > > > On 16/04/24 22:30, Tom Rini wrote: >> On Tue, Apr 16, 2024 at 05:52:58PM +0530, Chintan Vankar wrote: >>> >>> >>> On 12/04/24 03:37, Tom Rini wrote: >>>> On Wed, Apr 03, 2024 at 06:18:01PM +0530, Chintan Vankar wrote: >>>>> >>>>> >>>>> On 22/01/24 10:11, Siddharth Vadapalli wrote: >>>>>> >>>>>> >>>>>> On 20/01/24 22:11, Tom Rini wrote: >>>>>>> On Mon, Jan 15, 2024 at 01:42:51PM +0530, Siddharth Vadapalli wrote: >>>>>>>> Hello Tom, >>>>>>>> >>>>>>>> On 12/01/24 18:56, Tom Rini wrote: >>>>>> >>>>>> ... >>>>>> >>>>>>>>> The list of conditionals in common/spl/spl.c::board_init_r() should be >>>>>>>>> updated and probably use SPL_NET as the option to check for. >>>>>>>> >>>>>>>> Thank you for reviewing the patch and pointing this out. I wasn't aware of it. I >>>>>>>> assume that you are referring to the following change: >>>>>>>> >>>>>>>> if (IS_ENABLED(CONFIG_SPL_OS_BOOT) || CONFIG_IS_ENABLED(HANDOFF) || >>>>>>>> - IS_ENABLED(CONFIG_SPL_ATF)) >>>>>>>> + IS_ENABLED(CONFIG_SPL_ATF) || IS_ENABLED(CONFIG_SPL_NET)) >>>>>>>> dram_init_banksize(); >>>>>>>> >>>>>>>> I shall replace the current patch with the above change in the v2 series. Since >>>>>>>> this is in the common section, is there a generic reason I could provide in the >>>>>>>> commit message rather than the existing commit message which seems to be board >>>>>>>> specific? Also, I hope that the above change will not cause regressions for >>>>>>>> other non-TI devices. Please let me know. >>>>>>> >>>>>>> Yes, that's the area, and just note that networking also requires the >>>>>>> DDR to be initialized. >>>>>>> >>>>>> >>>>>> Thank you for confirming and providing your suggestion for the contents of the >>>>>> commit message. >>>>>> >>>>> Following Tom's Suggestion of adding CONFIG_SPL_NET in common/spl/spl.c >>>>> "dram_init_banksize()", the issue of fetching a file at SPL stage seemed >>>>> to be fixed. However the commit "ba20b2443c29", which sets gd->ram_top >>>>> for the very first time in "spl_enable_cache()" results in >>>>> "arch_lmb_reserve()" function reserving memory region from Stack pointer >>>>> at "0x81FFB820" to gd->ram_top pointing to "0x100000000". Previously >>>>> when gd->ram_top was zero "arch_lmb_reserve()" was noop. Now using TFTP >>>>> to fetch U-Boot image at SPL stage results in "tftp_init_load_addr()" >>>>> function call that invokes "arch_lmb_reserve()" function, which reserves >>>>> entire memory starting from Stack Pointer to gd->ram_top leaving no >>>>> space to load U-Boot image via TFTP since TFTP loads files at pre >>>>> configured memory address at "0x82000000". >>>>> >>>>> As a workaround for this issue, one solution we can propose is to >>>>> disable the checks "lmb_get_free_size()" at SPL and U-Boot stage. For >>>>> that we can define a new config option for LMB reserve checks as >>>>> "SPL_LMB". This config will be enable by default for the backword >>>>> compatibility and disable for our use case at SPL and U-Boot stage. >>>> >>>> The problem here is that we need LMB for booting an OS, which is >>>> something we'll want in SPL in non-cortex-R cases too, which means this >>>> platform, so that's a no-go. I think you need to dig harder and see if >>>> you can correct the logic somewhere so that we don't over reserve? >>>> >>> Since this issue is due to function call "lmb_init_and_reserve()" >>> function invoked from "tftp_init_load_addr()" function. This function >>> is defined by Simon in commit "a156c47e39ad", which fixes >>> "CVE-2018-18439" to prevent overwriting reserved memory. Simon, can you >>> explain why do we need to call "lmb_init_and_reserve()" function here ? >> >> This is indeed a tricky area which is why Sughosh is looking in to >> trying to re-work the LMB mechanic and we've had a few long threads >> about it as well. >> >> I've honestly forgotten the use case you have here, can you please >> remind us? >> > We are trying to boot AM62x using Ethernet for which we need to load > binary files at SPL and U-Boot stage using TFTP. To store the file we > need a free memory in RAM, specifically we are storing these files at > 0x82000000. But we are facing an issue while loading the file since > the memory area having an address 0x82000000 is reserved due to > "lmb_init_and_reserve()" function call. This function is called in > "tftp_init_load_addr()" function which is getting called exactly before > we are trying to get the free memory area by calling > "lmb_get_free_size()".
I have no idea about your platform but I was wondering if there is any particular importance of the load address of 0x82000000? It looks as though the current location of the SP when arch_lmb_reserve() gets called means that the load address is getting reserved for the U-Boot image. Do you not have the option of loading the image at a lower address instead?
Sughosh,
I think my explanation was not clear at: "We are trying to boot AM62x using Ethernet for which we need to load binary files at SPL and U-Boot stage using TFTP."
- In Ethernet Booting we are fetching U-Boot image at SPL stage via
TFTP at specified address 0x82000000. While loading U-Boot image we are getting TFTP error, since address from stack pointer till gd->ram_top is reserved due to "lmb_init_and_reserve()" function call. I want to know for which purpose this address range is reserved.
On relocation, the U-Boot image is located typically at the top of the DRAM memory used by U-Boot(ram_top). That region of memory is reserved to ensure that the memory occupied by the U-Boot image does not get overwritten by a LMB reservation.
Yes, you are correct about U-Boot relocation but we are facing an issue at the time of fetching U-Boot proper at SPL stage.
The arch_lmb_reserve_generic() function would reserve the memory region from the ram_top to the current SP. Btw, you mentioned in an earlier reply that you are trying to load the U-Boot image at 0x82000000. From the config file it looks like that is the address of your SPL stack in RAM. So you might be overwriting your SPL stack. I think you can try a couple of things. One, move the SPL image above the SPL stack, like it is with U-Boot -- I think the way things stand,
Are you suggesting to relocate SPL image similar to U-Boot relocation. ?
the SPL image is at a lower address than the SP. And then use a lower address to load the U-Boot image with tftp.
-sughosh
Btw, are you facing this issue in SPL, or U-Boot proper? I built the images for the am62x_evm_a53 config, and I don't see the
We are getting "TFTP error" at runtime while fetching U-Boot proper at SPL stage while booting via "Ethernet", and we are using "am62x_evm_a53_ethboot_defconfig" instead of "am62x_evm_a53_defconfig".
These are the extra configs we are using on top of "am62x_evm_a53_defconfig":
CONFIG_SPL_DRIVERS_MISC=y CONFIG_SPL_BOARD_INIT=y CONFIG_SPL_DMA=y CONFIG_SPL_ENV_SUPPORT=y CONFIG_SPL_ETH=y CONFIG_SPL_NET=y CONFIG_SPL_NET_VCI_STRING="AM62X U-Boot A53 SPL" CONFIG_SPL_SYSCON=y
arch_lmb_reserve() function getting included in the SPL image -- both the .text.arch_lmb_reserve and .text.arch_lmb_reserve_generic are part of discarded sections. So I am wondering how you are observing this behaviour in SPL.
-sughosh
Or using a higher address for SPL stack? You might be able to solve this just by re-examining which addresses (and RAM size limitations) need to be considered here.
Tom,
We tried this approach of assigning a higher address for SPL stack, but it is not working as expected.